Field of the Disclosure
Embodiments disclosed herein relate generally to a choke trim for a choke valve used for controlling the flow of fluids.
Background Art
Choke valves are used to control the flow rate and the pressure of fluids flowing through a flow line in hydrocarbon wells. When a well is being drilled and stimulated, gases and drilling fluids under high pressure flow through the choke valve. The gases and drilling fluids may be at high pressures and may carry abrasive particles such as drill cuttings, sand, silt, drilling fluid additives, and other debris.
To protect the interior of the choke valve, choke valves generally include one or several inserts such as a trim. The trim is a replaceable component that is used to line the interior of the housing of the choke valve. It is made of an erosion-resistant material, such as tungsten carbide. Furthermore, the trim may serve as a valve seat. Referring to FIG. 1, an example of a prior art choke valve 1 is shown. The choke valve 1 includes a choke housing 3, a bonnet 21, a shuttle assembly 19 including a mandrel 17 and a shuttle 15 slidably mounted over the mandrel 17, a trim 9 having a flanged design and serving as a seat for the shuttle 15, a flange sleeve 13, and downstream trim components, such as a wear sleeve 11. The choke housing 3 includes an inlet channel 5, an outlet channel 7, and a choke orifice 27. The trim 9 is kept in place by an o-ring 29 sealing the trim 9 to the housing 3.
In the choke valve illustrated in FIG. 1, the flange sleeve 13 and the shuttle assembly 19 are aligned within the choke valve 1 with respect to an inner wall 28 of choke orifice 27, and the trim 9 is aligned with an inner wall 10 of the outlet channel 7. Consequently, if the choke orifice 27 and the outlet channel 7 were misaligned during manufacture of the housing 3, there would be misalignment of the shuttle assembly 19 and the trim 9. Since the trim 9 serves as a shuttle seat, mechanical pressure is exerted on the trim 9 by the shuttle 15 repeatedly. Misalignment could even lead to breakage of the trim 9. Furthermore, the distance between the o-ring 29 and the first end 37 of the trim 9 is relatively long so that mud and other materials may gather between the trim 9 and the choke housing 3. This may also result in misalignment of the trim 9 and may make it difficult to remove trim 9 for replacement as accumulated particles may wedge trim 9 in place.
In addition, to allow for manufacturing tolerances, a gap of up to 0.03 inches may exist between the inner diameter of the flange sleeve 13 and a first end 37 of the trim 9. Thus, the flange sleeve 13 does not retain the trim 9; rather, o-ring 29 is used to retain trim 9 with respect to housing 3. Due to this gap between the trim 9 and the flange sleeve 13, the trim 9 can move with respect to the flange sleeve 13, resulting in a loss of concentricity between the shuttle 15 and the trim 9.
In addition, the manufacture of the trim 9, being of an erosion-resistant material, such as tungsten carbide or hardened steel, is a difficult task due to its flanged design and the changing cross-sectional area of trim 9 throughout its length.
Thus, it would be an improvement to the art to have a trim with a simplified design and increased performance due to an improved fit of the trim within the choke valve.